A rookery with 300 turtle nests per season is considered to be a significant turtle…
Matthew Prophet, the Nature Conservation Co-ordinator of the Department of Environment and Conservation (DEC) Exmouth District and Colin Valentine, a ‘turtle tracker trainer’ with the Ningaloo Turtle Program in Exmouth, visited Gnaraloo during February 2011. The purpose of the visit was an information exchange between DEC and the GTCP. Gnaraloo’s Environmental Advisor (GEA) travelled to site from Geraldton to undertake site work with the GTCP team and host the DEC visit.
On 1 February 2011, as part of the information sharing, GEA and GTCP team members gave a PowerPoint presentation with an overview of the GTCP, scope of research 2008 – 2011 (including night surveys and crab population study), data collection procedures, the new community volunteer program, preliminary results to date.
On 2 February 2011, Matt and Colin joined GEA and GTCP researchers on the daily morning track patrol during which they witnessed the effects of Cyclone Bianca (27 – 28 January 2011, 39mm rain) on the monitored Gnaraloo Bay rookery. Interesting, the strong winds induced by Bianca had a more significant impact on the rookery than the heavy December rains but low strength winds experienced as a result of Cyclone Vence (16 – 17 December 2010, 237mm rain). Despite having devastating consequences for the local community in Carnarvon, the rain and subsequent flooding associated with Vence left the GTCP study area relatively unaffected.
On the contrary, unusually strong wave and tidal action caused by Cyclone Bianca led to significant erosion with steeper than usual sand cliffs along the majority of the monitored rookery as a result (particularly in the northern most section of it). Many turtle nests were washed away, with eggs and dead hatchlings strewn across the beach.
Most of the turtle beach activities recorded since then have resulted in unsuccessful nesting emergences, meaning that turtles still came onto the beach, but were unable to find suitable nesting habitat due to the new high sand cliffs and consequently returned to the water without laying eggs. This resulted in reduced nesting occurrences along the study area. It is not known whether these females went to other beaches to dig nests.
Towards the end of January saw a steady, rapid decline in turtle nests being dug along the monitored rookery, eventually leading to an almost complete cessation of nests after 26 January 2011. On 30 January 2011, there were 8 beach activities (unsuccessful nesting attempts and U Tracks only) but no actual nests. No beach activities were observed from 2 -7 February 2011. As a result, the formal monitoring period 2010/11 was ended on 7 February 2011 prior to the initially planned end date of 28 February 2011.
After a few rest days, the GTCP researchers 2010/11 said their goodbyes to Gnaraloo and its staff, and made their way to Geraldton for end-of-season technical data analysis and report writing, which will take place under GEA’s direct guidance and supervision.
Cheers, Mark and Marie